A Novel Heterostructure of BiOI Nanosheets Anchored onto MWCNTs with Excellent Visible-Light Photocatalytic Activity

Shijie Li,Jianshe Liu,Kaibing Xu,Zhaohui Wang,Shiwei Hu,Wei Jiang

doi:10.3390/nano7010022

Abstract

Developing efficient visible-light-driven (VLD) photocatalysts for environmental decontamination has drawn significant attention in recent years. Herein, we have reported a novel heterostructure of multiwalled carbon nanotubes (MWCNTs) coated with BiOI nanosheets as an efficient VLD photocatalyst, which was prepared via a simple solvothermal method. The morphology and structure were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS), and specific surface area measurements. The results showed that BiOI nanosheets were well deposited on MWCNTs. The MWCNTs/BiOI composites exhibited remarkably enhanced photocatalytic activity for the degradation of rhodamine B (RhB), methyl orange (MO), and para-chlorophenol (4-CP) under visible-light, compared with pure BiOI. When the MWCNTs content is 3 wt %, the MWCNTs/BiOI composite (3%M-Bi) achieves the highest activity, which is even higher than that of a mechanical mixture (3 wt % MWCNTs + 97 wt % BiOI). The superior photocatalytic activity is predominantly due to the strong coupling interface between MWCNTs and BiOI, which significantly promotes the efficient electron-hole separation. The photo-induced holes (h+) and superoxide radicals (O2−) mainly contribute to the photocatalytic degradation of RhB over 3%M-Bi. Therefore, the MWCNTs/BiOI composite is expected to be an efficient VLD photocatalyst for environmental purification.

Highlights

Semiconductor photocatalysis is an effective means to tackle the energy crisis and environmental problems by splitting water to produce H2 and degrading various organic contaminants in water/air [1]
The broad peak at 2θ = 26.3◦ is assigned to the characteristic peak of multiwalled carbon nanotubes (MWCNTs) [47,48]
A desired amount of MWCNTs was ultrasonically dispersed in the mixture (30 mL ethylene glycol + 10 mL absolute ethanol)

Summary

Introduction

Semiconductor photocatalysis is an effective means to tackle the energy crisis and environmental problems by splitting water to produce H2 and degrading various organic contaminants in water/air [1]. To further improve its photocatalytic activity, many kinds of BiOI-based composites have been developed, including BiOI-oxide (oxide: Fe2 O3 [20], TiO2 [21,22], WO3 [23] BiOBr(Cl) [24,25], BiVO4 [26], Bi12 O17 Cl2 [27], Bi2 W(Mo)O6 [28,29], BiOIO3 [30], Bi4 Ti3 O12 [31], BiPO4 [32]), BiOI-sulfide (sulfide: CdS [33], Bi2 S3 [34]), BiOI-metal (metal: Ag [35]), BiOI-carbon (carbon: graphene [36,37,38,39], carbon quantum dots [40]), and multi-component (e.g., BiOClx/BiOBry/BiOIz [41], MoS2 /AgI/BiOI [42], Ag3 VO4 /Ag/BiOI [43]) These composites all show relatively higher activity than pure BiOI in degrading organic contaminants, Cr(VI) reduction, and/or hydrogen production. The BiOI-carbon composites have been demonstrated to be excellent photocatalysts, but they are still underdeveloped [36,37,38,39,40]

Methods

Results

Conclusion